* Windows
To successfully run =scripts/build_externals.py= on Windows, the following
tools and dependencies must be installed and available in =PATH=.

** Required software
1. **Python 3.10+**  
   Install Python and create/activate a virtual environment for Mizuki.

   #+BEGIN_SRC sh
   python -m venv venv
   venv\Scripts\activate
   #+END_SRC

2. **MinGW-w64**  
   Install or download a recent MinGW-w64 toolchain (example: 13.2.0).  
   Ensure that =<mingw-root>\bin= is in your PATH.

   Example:
   #+BEGIN_SRC bat
   set PATH=C:\toolsets\mingw64-13.2.0\mingw64\bin;%PATH%
   #+END_SRC

3. **MSYS2**  
   Download from https://www.msys2.org/ and install to the default location (=C:\msys64=).

** MSYS2 packages
After installing MSYS2, open a MSYS2 shell and run:

#+BEGIN_SRC sh
pacman -Syu
pacman -S perl
pacman -S mingw-w64-x86_64-openssl
pacman -S make
#+END_SRC

This ensures that OpenSSL’s build system has a compatible Perl and
that =build_externals.py= can configure and build OpenSSL.

** Environment requirements before building
Before running =scripts/build_externals.py= you must:

- Activate the Mizuki Python venv.  
- Have your chosen MinGW toolchain’s =bin= directory in PATH.  
- Have MSYS2’s =usr\bin= in PATH (for =perl=).  

Example session:

#+BEGIN_SRC bat
REM Activate venv
call venv\Scripts\activate.bat

REM Add MinGW to PATH
set PATH=C:\toolsets\mingw64-13.2.0\mingw64\bin;%PATH%

REM Add MSYS2 Perl to PATH
set PATH=C:\msys64\usr\bin;%PATH%

REM Build externals
python scripts\build_externals.py
#+END_SRC